1. Field of the Invention
The field of the invention relates generally to transmissions, and more particularly the invention relates to continuously variable transmissions.
2. Description of the Related Art
In order to provide a continuously variable transmission, various traction roller transmissions that transmit power through traction rollers supported in a housing between torque input and output discs have been developed. In such transmissions, the traction rollers are mounted on support structures which, when pivoted, cause the engagement of traction rollers with the torque discs in circles of varying diameters depending on the desired transmission ratio.
The use of a driving hub for a vehicle with a variable adjustable transmission ratio is known. In some instances a transmission uses iris plates to tilt the axis of rotation of the rollers. Other transmissions include a shaft about which an input disc and an output disc rotate. The input and output discs mount on the shaft and contact balls disposed equidistantly and radially about the shaft. The balls are in frictional contact with both discs and transmit power from the input disc to the output disc. An idler located concentrically over the shaft and between the balls aids in maintaining frictional contact between the balls and the input and output discs.
Wind turbines usually have drive trains that include gearboxes for managing power transfer from a rotor to a generator. Continuously variable transmissions such as those described below offer advantages to improve the performance and efficiency of wind turbines, typically resulting in lower cost of energy production.